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There's Another Linux Kernel Power Problem

Phoronix: There's Another Linux Kernel Power Problem

After last year discovering a major Linux kernel power regression that was widely debated until the Phoronix test automation software bisected the problem to get to the bottom of the situation, there's more active power regressions today on the Linux desktop. As I've mentioned on Twitter and in other articles in weeks prior there's a few regressions, but one of them for at least some notebooks is causing a very significant increase in power consumption. This situation that remains unresolved as of the Linux 3.7 kernel can cause the system to be going through about 20% more power.

Given that 3.7 lacks drops that the others have, maybe it's a cpuidle regression?

Or maybe the scheduler is migrating cores too much, not keeping all the cores at a higher frequency than they would normally be? Can easily check that with perf. I did see http://klaig.blogspot.com/2012/12/fo...-can-make.html today, but the versions listed aren't consistent with this, though perhaps there was a minor regression in 3.6 that was amplified by some change in 3.7.

Not sure if this is the same thing but,

I have been testing 3.7 since the rc1, and later in the development I started noticing power issues on my Asus X53E with the Sandy Bridge graphics. I finally noticed that powertop 2.1 would report the GPU running 100 percent of the time, and the exhaust was running hot also. I checked the DMESG, and it did show that the i915 kernel module was enabling the sleep states, but obviously it wasn't working..

normally a reboot of the laptop would temporarily fix the issue, least until I tried booting the unit cold again..

only other issue is that 3.6 and 3.7 don't seem to work right with reboots, and power off, I have to manually turn it off with the switch. 3.5 doesn't have any of these issues.

when running 3.7 without the gpu bugging, I am getting much better power usage, normally idles under 8 watts, where normally I get 8.2 watts according to powertop or the gnome power monitor.

I have been testing 3.7 since the rc1, and later in the development I started noticing power issues on my Asus X53E with the Sandy Bridge graphics. I finally noticed that powertop 2.1 would report the GPU running 100 percent of the time, and the exhaust was running hot also. I checked the DMESG, and it did show that the i915 kernel module was enabling the sleep states, but obviously it wasn't working..

normally a reboot of the laptop would temporarily fix the issue, least until I tried booting the unit cold again..

only other issue is that 3.6 and 3.7 don't seem to work right with reboots, and power off, I have to manually turn it off with the switch. 3.5 doesn't have any of these issues.

when running 3.7 without the gpu bugging, I am getting much better power usage, normally idles under 8 watts, where normally I get 8.2 watts according to powertop or the gnome power monitor.